Cymbidium Orchids

Cymbidium Orchids Cymbidiums are most popular orchids in temperate climate regions of Australia. They are easily grown; their colorful, long lasting flowers are suitable for home decoration. The advances in plant and flower quality have been brought about by commercial development of Cymbidiums, both for the domestic and overseas markets, and indeed, it was the race to develop and expand the export market since the 1960’s which has resulted in many of the finest orchids we have available today. Cymbidiums also come with a range of spike habits, varying from the stiffly upright to the decorative pendulous types, depending on variety. Flower count on the spike can vary dramatically, too, depending on the particular clone. Cym Burma Star Once you have selected your first Cymbidium, you will find that there are many types you can grow. The earliest ones, flowering from late autumn, are scarcer, hence more valuable for flower sales. A dramatic improvement has resulted in the quality of winter flowering Cymbidiums due to commercial pressures, and flower quality is now as good as that of mid-late season blooms. All the foregoing variations occur in plants with differing size blooms and growth habit, which for judging purposes have been grouped into miniature, intermediate, and standard (large) types. So you can see there is a variety of Cymbidium from which to choose. GROWING CONDITIONS Many of the parent species of today’s hybrid Cymbidiums originate in the Himalayan foothills, with warm sunshiny days, summer rains with high humidity, and cool nights. Our climate suits them very well provided a few basic conditions are met. HOUSING YOUR PLANTS Most Cymbidium growers provide shade houses in which to grow their plants. The aim is to supply a fresh, buoyant atmosphere for the plants whilst providing them with some protection from direct sun and hail in the winter. A frame work about two and a half metres high covered with 50% shade cloth to ground level, away from overshadowing trees or buildings will suit them well. Cym Flaming Pepper Plants are generally placed on low benches, with shavings or gravel, which can be kept damp underneath. This helps to provide the summer humidity, which your Cymbidiums enjoy. Overhead sprinklers are almost a necessity with large collections, but for smaller ones, the personal touch of watering by hose will help you monitor the plants’ development more closely. Space your plants so that all the leaves and bulbs receive maximum sunlight and air movement. Plants too close together don’t flower as well. If you only have a few Cymbidiums, they will grow well under dappled shade of a lemon or other light foliaged tree. Stand the pots on a galvanized frame about two house bricks high to discourage slugs, snails, and worms that can ruin your potting mix and providing you keep the plants well watered through the summer, and give them regular feeding, you, too, can achieve good results. Once the flower spikes start extending, it is time to shift them under glass or other protection. This will shelter the tender buds from wind or rain damage, and you can protect them better from aphids or slug damage. Good air movement around your plants and adequate light are still high priorities at this time of year. LIGHT CONDITIONS Lack of sunlight is the most common reason why Cymbidiums fail to flower well along the East Coast of Australia. Shade cloth which gives 50% direct sunlight for the whole of the day is perhaps the best compromise, although extreme hot summer sun will scorch the leaves unless supplementary shade can be provided. Conversely, shading from trees or buildings for part of the day, or too close crowding of the plants, will reduce flower spike production. -1-

Adequate sunlight will maintain a golden green colour in the leaves on more robust plants, rather than darker green leaves which are longer and weaker where shading is too heavy. Non flowering plants should be given as much light as possible, short of burning the leaves, and if only a few plants are involved, can be lifted around to provide full sunlight in winter. Take care, though, to protect them from frosts, which can cause defoliation of the older pseudobulbs. Cym Pastel Queen WATERING AND FERTILISING Cymbidiums do best in an open, free draining potting medium, and should be watered heavily during the warmer months when plants are growing most strongly. Even in winter they should be kept moist. Rain water gives the best results with least leaf die back, but even hard, saline water is satisfactory if care is taken to water heavily so that water drains freely from the bottom of the pots. This helps ensure that any salt build up in the potting mix is leached from the pot. Excessive salt build up leads to root tip burn and leaf tip die back, and retards growth of the plant. A good potting practice with poor water quality is to leave a 2cm space between the top of your potting mix and the rim of the pot. When watering, fill the pot to the brim, allow draining then repeating the process. Ensure, though, that the potting mix fully covers the roots of your plant. Small pots dry out faster than larger ones, so it is good practice to group plants depending on their pot size, so differing water needs can be met. The study of the Cymbidium orchid’s fertilizer requirements has led to varying the chemical ratio of the principal elements of the fertilizer (nitrogen, phosphorous and potash) at different times of the year; high nitrogen for early growth, high phosphorus and potash at spike initiation time, and more balanced composition whilst the pseudobulbs and spikes are maturing. The aim of all feeding is to supply the plant with adequate nutritional needs without overdosing and consequent root burn. POTTING MEDIUM The Cymbidium is a semi-terrestrial orchid with fleshy roots. The potting medium should therefore be free draining, but should some retain moisture to nourish the plant whilst supporting it firmly in the pot. Practical experience will lead to modification of the basic mix to give you best results with your watering practices and growing conditions. Some plants develop vigorous root systems, which run around the inside of pots. They should be untangled before shifting the plant to a larger pot. Large plants with extensive roots and requiring division are best handled by slicing off the bottom 25% of the intertwined root mass. The remaining roots will be more easily freed, with less damage. Once the old potting mix has been shaken from the roots, the point where the rhizomes at the base of the pseudobulbs should be separated to give reasonable sized divisions will become apparent. Always try to keep at least one division with three or four green bulbs with leaves intact, to give best prospects of flower spikes next season. Provided the front bulbs have adequate roots, the old leafless back bulbs can be carefully broken away from the rest of the plant. If growth “eyes” remain on the lower part of these back bulbs, they can have old leaf tissue and roots removed and then potted up to half their depth. They will then produce new shoots, which grow on, to give you a new division of your plant. The lowest eyes produce the best and strongest shoots, so take care when cleaning up the old bulbs. Back bulb propagation was once one of the most popular and cheapest ways of increasing collections, but more recently, divisions of the best Cymbidiums are readily available as mericlones. Mericlones are just divisions of a particular orchid grown through a specialised process of cultivating the growing shoot tips of the plant under sterile laboratory conditions. The developing tissue is divided a number of times, and the bits are then grown on to produce replicas of the original plant. In Almost all cases the new plants are true to the type, but excessive redividing can sometimes give rise to genetic mutations which cause variation in the floral parts.

Cym Golden Elf ‘Sundust’ -2-

The best time for repotting or dividing large plants is immediately after the flowering season, when your divisions will have a long growing season to develop before producing next season’s blooms. Smaller plants can be potted on or repotted at most times of the year, but avoid potting when the forecast is for hot weather. Once potted, the plants should be given more sheltered conditions for a week or two, then return to your main growing area.

FLOWERING YOUR CYBIDIUMS New growth shoots on Cymbidiums develop from mature pseudobulbs. These growths progress strongly in spring when the old flower spike is removed from the plant. If through good culture you are able to develop the new shoots by the end of November to about 40cm long, preferably starting to swell at the base, and if you can supply an overnight temperature drop by watering in the evenings, you give your plants the best chance of flowering the next season. When the new spikes are small, it is often difficult to tell whether you have new growth shoots or flower spikes. Presentation of the flowers on the stem is enhanced with careful support of the developing spikes with stakes and twisties. If you move your plant, ensure that the spikes are realigned towards the strongest light. This will avoid twisted stems, because the lengthening spikes turn towards the main light source. Clarity and depth of colour of your blooms can be influenced by the amount of light you allow to fall on the developing buds. Generally, give the deep pinks, yellows and reds as much light as possible to enhance the intensity of colour. Conversely, greens and whites require shading to prevent sun marking on the backs of the flowers. Avoid too heavy shading however, which will result in smaller blooms lacking in substance on weak stems. As a general rule, the more light your plants receive, the stronger and sturdier the spikes and blooms will be. Once the flowers open, shading the spikes will retain the colours better. Cym Lamorack When your blooms have been fully out for about a week, you can consider whether the spikes should be removed. The growth eyes at the base of the bulbs will develop much more quickly, giving you a longer growing season to produce next season’s flowers. The cut spikes will still last well if placed in fresh water in a cool room. It is an unfortunate fact that many people buying a Cymbidium orchid in bloom for the first time are so enthralled by its beauty that they bring it inside, and there it remains until the flower dies. For Cymbidiums, this is the wrong thing to do. Two or three days indoors is more than enough. It is far better to pick the flowers; they will last a long time in a vase and the plant can be outside in the conditions it likes best. There it will start preparing for next year’s flowers. These notes have been used at our Cultural and New Grower’s Meetings. They are from various sources and we thank the authors. All articles are supplied in good faith and the Bribie Island Orchid Society and its members will not be held responsible for any loss or damage.

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